$\begingroup$As a small recommendation, linked with Rubio's answer, if the January 2018 puzzle's hint also applies to this question, it would be better to also place it. It's better to get a repeated hint than a missing yet important hint$\endgroup$
– BelhenixApr 2 at 22:30

2

$\begingroup$@Belhenix I added that hint as well as one more. I'll keep this in mind for all future puzzles too, thanks!$\endgroup$
– Tyler22AlexApr 3 at 0:32

8 Answers
8

Neil Armstrong was the first man on moon. Armstrong number is an n-digit number in which sum of n-th power of each digit is equal to the number itself.
E.g. - 371 = 3^3 + 7^3 + 1^3. (3 digit number so power of 3).

Using this rationale, we find that

115132219018763992565095597973971522401 is the largest known armstrong number as per this and has 39 digits.

$\begingroup$Nice job! You got it! Side note: I actually used this (and all other password puzzles I post) as my password and I don't think I've forgotten one yet :) I like numbers!$\endgroup$
– Tyler22AlexApr 3 at 14:29

$\begingroup$On the right track with Armstrong, but looking in the wrong direction for the number. Maybe what you've got so far and my second hint will get you closer!$\endgroup$
– Tyler22AlexApr 3 at 4:31

Luna 2 was the first spacecraft to make contact with the moon.
According to Wikipedia, Luna 2 was engraved with "1959 январь" and "СОЮЗ СОВЕТСКИХ СОЦИАЛИСТИЧЕСКИХ РЕСПУБЛИК"1, making "1959" the first number on the moon.
Furthermore, phone passcodes are typically 4 digits long, so using a year as a passcode makes sense.

Apollo 11 was the first manned mission to the moon, and it had the “largest number” of anything that was first to the moon, greater that Luna 2, which was the first successful unmanned spacecraft to land.

There are a lot of ways to find numbers that are "first on the moon", so this question may need some more specificity to rule out answers; right now there doesn't seem to be any criteria beyond "the largest" number an answerer might justify somehow, which is probably too broad.

It's possible the password is

201901030226

We know that

OP uses passwords that are usually pretty long, as we learned in Unlock My Phone! January 2018.
We're looking for the largest "first on the moon" number.

If we take the date and time, in GMT, of this moon landing, we get 201901030226. Seconds were not given, so this is the most specific timedate stamp we can get.

Since this is the most recent moon landing, if we were to consider any other "first" - by nation, by mission type, whatever - and take their corresponding YYYYMMDDHMM number, this one would be the largest.